The decomposition of an environmentally recalcitrant s-triazine compound, prometry (PMT), was carried out by experimental and theoretical approaches to study the combined effects of hydroxyl radicals (center dot OH) and hydrated electrons (e(aq)(-)). With the participation of strongly oxidative radicals (OH)-O-center dot and reductive radicals e(aq)(-) induced by electron beam (EB), PMT obtained a good decomposition performance, which was obviously better than those methods simply using (OH)-O-center dot as the single active species. The evolution of cyanuric acid (CA) during the EB and UV irradiation processes elucidate that former method could efficiently decompose such chemically stable intermediate. The experiments of radical scavengers further suggest that (OH)-O-center dot was the predominant radical during PMT degradation, while e(aq)(-) was beneficial to further decomposition and mineralization. Combined with the results of density functional theory (DFT) calculations, the strengthened synergistic effects between (OH)-O-center dot and e(aq)(-) were proven. The calculations illustrated (OH)-O-center dot could attack the carbon-branch-chains of s-trazine ring and form OH-adducts rather than nitrogen oxides. Moreover, the presence of e(aq)(-) could not only greatly change the geometry of the s-triazine ring, but also help cleaving alkyl chain on ring, thus facilitate the complete mineralization. (C) 2017 Elsevier Ltd. All rights reserved.